1. Field of the Invention
This invention relates to an energy saving cooling system for a building structure and in particular to such a cooling system that provides thermal storage and passive cooling through the floor of the structure.
2. Description of Related Art
An energy saving protected roof system is described in U.S. Pat. No. 5,174,128 to Bourne et al., which is herein incorporated by reference. The Bourne et al. system includes a waterproof membrane on a roof deck, a reservoir defined by the waterproof membrane containing a liquid, at least one insulating panel adapted to float on the reservoir and covering the waterproof membrane, pumping means having an inlet within the reservoir and an outlet communicating with the surrounding environment for selectively distributing liquid from the reservoir onto the external surface of the panel, drain means through the panel for permitting drainage of liquid in the external surface into the reservoir and overflow drainage means extending through the roof for establishing a desired depth of the reservoir. The Bourne et al. system reduces cooling costs on buildings through night evaporative and radiative cooling of the liquid reservoir by spraying the liquid at night on top of the insulation to cool the liquid. Significant radiative cooling occurs because the night sky is typically at least 30 degrees cooler than the night air in fairly dry areas such as the southwestern part of the United States. The cooled liquid drains through the drain means and returns to the water reservoir. During the day, the cooled water minimizes roof temperature variations and decreases heat transfer from the roof to the interior of the structure.
The roof-reservoir system requires significant modifications to conventional construction, since a "dead level" structure is necessary. Also, direct cooling of the structure through the roof is not efficient if the roof deck is not exposed to the interior of the structure, in which case the reservoir would not be in heat exchange relationship with the interior of the structure.